Changes In Resource Utilization Research Articles

Enhancing recovery after minimally invasive repair of pectus excavatum.

There are variations in the perioperative management of patients who undergo minimally invasive repair of pectus excavatum (MIRPE). The purpose is to analyze the change in resource utilization after implementation of a standardized practice plan and describe an enhanced recovery pathway. A standardized practice plan was implemented in 2013. A retrospective review of patients who underwent MIRPE from 2012 to 2015 was performed to evaluate the trends in resource utilization. A pain management protocol was implemented and a retrospective review was performed of patients who underwent repair before (2010-2012) and after (2014-2015) implementation. There were 71 patients included in the review of resource utilization. After implementation, there was a decrease in intensive care unit length of stay (LOS), and laboratory and radiologic studies ordered. There were 64 patients included in the pain protocol analysis. After implementation, postoperative morphine equivalents (3.3±1.4 vs 1.2±0.5mg/kg, p<0.01), urinary retention requiring catheterization (33 vs 14%, p=0.07), and LOS (4±1 vs 2.8±0.8days, p<0.01) decreased. The implementation of an enhanced recovery pathway is a feasible and effective way to reduce resource utilization and improve outcomes in pediatric patients who undergo minimally invasive repair of pectus excavatum.

Incremental Effect of the Addition of Prescriber Restrictions on a State Medicaid's Pharmacy-Only Patient Review and Restriction Program.

Patient review and restriction programs (PRRPs), used by state Medicaid programs to limit potential abuse and misuse of opioids and related controlled medications, often restrict members to a single pharmacy for controlled medications. While most states use a restricted pharmacy access model, not all states include restricted prescriber access. Oklahoma Medicaid (MOK) added a restricted prescriber access feature to its PRRP in July 2014. To evaluate the incremental effect that the addition of a prescriber restriction to MOK's pharmacy-only PRRP had on the pharmacy and resource utilization of the enrolled members. MOK members with at least 6 months of enrollment in the pharmacy-only PRRP were restricted to a maximum of 3 prescribers for controlled substances in July 2014 and were identified as "cases." Using a propensity score method, cases were matched to controls from the MOK non-PRRP enrolled population based on demographics and baseline health care utilization. Data from January 1, 2014, through December 31, 2014, were evaluated. Each member's monthly health care resource utilization, defined in terms of medical and pharmacy costs, prescription counts, and opioid use per member per month (PMPM), was analyzed. A difference-indifferences (DID) regression estimated the change in resource utilization following the July 2014 policy change. This study included 378 controls and 126 cases after propensity matching. No differences were noted for daily morphine equivalents, benzodiazepine prescriptions, or maintenance prescriptions. There were decreases in mean PMPM use for both groups for short-acting opioid (SAO) claims (P < 0.001), overall opioid claims (P = 0.007 for controls and P < 0.001 for cases), prescribers (P = 0.01 for controls and P < 0.001 for cases), and number of pharmacies for cases (P < 0.001). DID analyses indicated that cases had a larger decrease in mean SAO claims (difference: -0.15, 95% CI: -0.25 to -0.04, P = 0.008); prescribers (difference: -0.25, 95% CI: -0.36 to -0.15, P < 0.001); and pharmacies (difference: -0.20, 95% CI: -0.28 to -0.13, P < 0.001) relative to controls. The difference for overall opioid claims was greater for cases than controls but did not reach statistical significance (difference: -0.12, 95% CI: -0.25 to 0.00, P = 0.050). Although there was no evidence that overall opioid claims were affected, the addition of prescriber restrictions may have resulted in an incremental change to SAO, prescriber, and pharmacy use in the PRPP population. Use of PRRPs may be an effective tool in reducing inappropriate use of prescription opioids within payer systems. The question remains whether these changes result in long-term changes to behavior outside the payer system. Future research into the effects of PRRPs on patient behavior beyond the payer system is needed. No outside funding supported this research. All authors disclose either employment by the Oklahoma Health Care Authority or contractual work for this employer. In addition, Keast discloses unrelated funding through unrestricted research grants from Gilead Sciences and Purdue Pharma. Study concept and design were contributed by Keast and Pham, along with Teel and Nesser. Keast and Pham collected the data, along with Teel, and data interpretation was provided by Keast and Pham, with assistance from Teel and Nesser. The manuscript was written primarily by Keast, along with Pham and Teel, and revised by all the authors.

Performance of spring wheat lines near-isogenic for the reduced-tillering ‘tin’ trait across a wide range of water-stress environment-types

Agronomically-important traits were studied in 19 genetically-diverse sets of spring wheat (Triticum aestivum L.) lines near-isogenic (NILs) for the tiller inhibition gene (tin) in contrasting water-stress environment-types (ETs) in the Australian grainbelt between 2010 and 2014. The combination of NILs and ETs generated a wide range of spike numbers (103 to 885 spikes/m2), grain numbers per m2 (GNO; 1400 to 22800 grains/m2), and grain yields (0.3 to 8.2t/ha). On average, the presence of tin significantly reduced spike numbers (319 vs. 381 spikes/m2), increased the numbers of grains/spike (30 vs. 27 grains/spike), and thousand grain weight (TGW; 38.4 vs. 36.9g) at maturity. Variation in final biomass and GNO each explained over 70% of the genotypic variation in grain yield. Differences in anthesis biomass explained 38% of the variation in grain yield. The marginal yield response to increases in GNO was slightly greater in the tin-containing lines while the response to increases in final biomass was greater in the non-tin lines (p≤0.016). The harvest index varied with changes in ET (p<0.001) only. The interaction between presence/absence of tin and environment-type was significant for grain yield, total biomass, spike number, grains/spike, and GNO. Grain yields were similar between NIL groups in the lower-yielding ETs (mean yield <2t/ha) whereas non-tin lines were higher-yielding in more favourable ETs (mean yield >2t/ha). The rate of the response in grain yield, total biomass, spike number, and GNO to changes in environmental conditions from ‘unfavourable’ to ‘favourable’ was significantly greater in the non-tin lines, i.e. tin-containing genotypes were less responsive or plastic. Reduced-tillering plasticity was associated with increased plasticity in numbers of grains/spike and, to a lesser extent, TGW. The tin lines produced more grains/spike in ETs averaging 28 to 33 grains/spike while NIL groups had similar grains/spike in ETs with lower means. A slightly greater marginal yield response to increases in GNO in tin lines indicated that greater plasticity in the number of grains/spike and TGW can compensate for reduced spike numbers. It is concluded that large variability in adaptation exists within the group of tin-containing genotypes providing opportunities for further selection to improve wheat performance in environments yielding less than 2t/ha. Further work on the analysis of GNO and yield determination in tin wheat should also consider changes in resource utilisation and hence competition between plants as mediated by planting arrangement.

Implementing shared decision-making: consider all the consequences.

BackgroundThe ethical argument that shared decision-making is “the right” thing to do, however laudable, is unlikely to change how healthcare is organized, just as evidence alone will be an insufficient factor: practice change is governed by factors such as cost, profit margin, quality, and efficiency. It is helpful, therefore, when evaluating new approaches such as shared decision-making to conceptualize potential consequences in a way that is broad, long-term, and as relevant as possible to multiple stakeholders. Yet, so far, evaluation metrics for shared decision-making have been mostly focused on short-term outcomes, such as cognitive or affective consequences in patients. The goal of this article is to hypothesize a wider set of consequences, that apply over an extended time horizon, and include outcomes at interactional, team, organizational and system levels, and to call for future research to study these possible consequences.Main argumentTo date, many more studies have evaluated patient decision aids rather than other approaches to shared decision-making, and the outcomes measured have typically been focused on short-term cognitive and affective outcomes, for example knowledge and decisional conflict. From a clinicians perspective, the shared decision-making process could be viewed as either intrinsically rewarding and protective, or burdensome and impractical, yet studies have not focused on the impact on professionals, either positive or negative. At interactional levels, group, team, and microsystem, the potential long-term consequences could include the development of a culture where deliberation and collaboration are regarded as guiding principles, where patients are coached to assess the value of interventions, to trade-off benefits versus harms, and assess their burdens—in short, to new social norms in the clinical workplace. At organizational levels, consistent shared decision-making might boost patient experience evaluations and lead to fewer complaints and legal challenges. In the long-term, shared decision-making might lead to changes in resource utilization, perhaps to reductions in cost, and to modification of workforce composition. Despite the gradual shift to value-based payment, some organizations, motivated by continued income derived from achieving high volumes of procedures and contacts, will see this as a negative consequence.ConclusionWe suggest that a broader conceptualization and measurement of shared decision-making would provide a more substantive evidence base to guide implementation. We outline a framework which illustrates a hypothesized set of proximal, distal, and distant consequences that might occur if collaboration and deliberation could be achieved routinely, proposing that well-informed preference-based patient decisions might lead to safer, more cost-effective healthcare, which in turn might result in reduced utilization rates and improved health outcomes.

The effect of a diabetes collaborative care management program on clinical and economic outcomes in patients with type 2 diabetes.

Clinical pharmacy services (CPS) in the primary care setting have been shown to help patients attain treatment goals and improve outcomes. However, the availability of CPS in community-based primary care is not widespread. One reason is that current fee-for-service models offer limited reimbursement opportunities for CPS in the community setting. Furthermore, data demonstrating the value of CPS in this setting are limited, making it difficult for providers to determine the feasibility and sustainability of incorporating CPS into primary care practice. To (a) evaluate the association between a pharmacist-led, diabetes collaborative drug therapy management program and patient outcomes, including glycemic control and health care costs, and (b) assess short-term economic outcomes in a primary care setting. A retrospective cohort analysis was conducted using medical record data. This study was conducted using patients with uncontrolled type 2 diabetes (T2DM), defined as HbA1c ≥ 7.0%. Outcomes were compared between patients referred to a diabetes collaborative care management (DCCM) intervention from 2009-2012 and patients who did not participate in the DCCM program. To illustrate the difference in HbA1c between the 2 cohorts over the follow-up period, mean time adjusted HbA1c values were estimated using a panel-type random effects regression model, with results plotted at 90-day intervals from index date through the end of the study period. To help control for confounding by other factors, multivariate regression models were run. A difference-in-difference model was employed to estimate the effect of the program on resource utilization and all-cause charges. A total of 303 DCCM and 394 comparison patients were included. Mean (95% CI) age was 57.4 years (55.963, 58.902) versus 59.9 years (58.613, 61.276; P < 0.001) with 48% and 44% female for DCCM and comparison patients, respectively (P = 0.49). Mean baseline HbA1c was higher for DCCM (10.3%; 10.10, 10.53) than comparison patients (8.4%; 8.26, 8.61; P < 0.001). The greatest reduction in HbA1c was seen for both groups at 9 and 12 months post-index date. At these time points, the mean time adjusted difference in HbA1c between groups was no longer significant. Multivariate modeling identified that the DCCM program was associated with a -0.44% (-0.64, -0.25; P < 0.001) lower HbA1c at follow-up relative to the comparison group controlling for potential confounders, including baseline HbA1c. Change in resource utilization from pre- to post-index date did not differ between groups. However, in the difference-in-difference multivariate analysis the difference in mean all-cause charges from the 12-month pre- to post-index periods DCCM patients experienced a smaller average increase in charges ($250) than comparison patients ($1,341; coefficient = -0.423; 95% CI = -0.779, -0.068). A pharmacist-led diabetes collaborative care management program in a patient-centered primary care setting was associated with significantly better follow-up glycemic control relative to comparison patients. Further, the data suggest that the DCCM program was associated with a less substantial increase in all-cause total costs in patients with uncontrolled T2DM relative to comparison patients, which could translate into reduced costs and improved outcomes to managed care payers.

Evaluation of insulin initiation on resource utilization and direct costs of treatment over 12 months in patients with type 2 diabetes in Europe: results from INSTIGATE and TREAT observational studies

Objectives:To describe the changes in resource utilization in seven European countries (Germany, Greece, Portugal, Romania, Sweden, Spain, and Turkey) and direct costs in four European countries (Germany, Spain, Sweden, and Greece) over the first 12 months of insulin treatment in patients with type 2 diabetes mellitus (T2DM).Methods:INSTIGATE and TREAT (2005–2010) were non-interventional, prospective, observational studies in patients with T2DM and initiating insulin for the first time. A 6-month retrospective data capture was conducted at baseline (insulin initiation) followed by prospective data collections at ∼3, 6, and 12 months. Statistical analyses were descriptive; estimated costs are presented as nominal values.Results:This study presents data for 1450 patients. Overall, in the first 6 months after insulin initiation, the use and cost of blood glucose monitoring and insulin increased, while the cost of oral diabetic medication decreased. Contributors to total direct costs differed between countries. Ranges of total mean direct costs over the 6-month period before insulin initiation were €489.10–€658.50 (Greece–Spain); 0–6 months after insulin initiation, €573.40–€1084.70 (Greece–Spain); and 6–12 months after insulin initiation, €495.80–€859.30 (Greece–Germany). Thus, the mean cost of treatment increased in all countries in the first 6 months after insulin initiation and then returned to baseline except in Germany.Limitations:Overall, 15% of patients were lost to follow-up over 12 months. Costs were not pro-rated to account for variation of visits. Participating centres may not have been fully representative of all levels of care.Conclusions:Contributors to total cost differed between countries, potentially reflecting local clinical practice patterns and insulin regimens. In each country, mean direct total costs of T2DM care increased during the first 6 months after insulin initiation and decreased thereafter.

Resource use and costs in the last year of life among Medicare beneficiaries who died from prostate cancer versus with the disease between 2000 and 2007.

6631 Background: Prostate cancer is one of the leading sources of overall cancer care costs among men in the United States. Medical resource use and costs associated with prostate cancer care at the end of life, remain poorly understood. Methods: Retrospective analysis of Surveillance, Epidemiology, and End Results (SEER) -Medicare data was used to characterize changes in resource utilization and health care costs to the Centers for Medicare and Medicaid (CMS) in patients diagnosed with prostate cancer who died of prostate cancer vs. non-prostate causes between 2000 and 2007. Results: A total of 34,727 patients with prostate cancer met study criteria. Patients who died of prostate cancer were significantly more likely to have been diagnosed with incident distant metastatic disease (27% vs. 4%) and had fewer comorbid conditions than patients who died of other causes. In the year prior to death, men who died of prostate cancer had lower mean inpatient costs ($20,769 vs. $29,851), resulting from fewer hospitalizations (1.8 vs. 2.1) and fewer days spent in the hospital (12.2 vs. 15.7) and the ICU (1.4 vs. 3.4) as compared to men who were diagnosed with prostate cancer but died of some other cause (all P&lt; 0.001). Men who died of prostate cancer also had lower rates of SNF utilization (32.8% vs 36.2%) and spent fewer days in SNF institutions (11.7 vs 14.7) (both P&lt; 0.001). Conversely, men who died of prostate cancer were more likely to have enrolled in hospice (62% vs. 28%) with higher mean hospice costs ($5,117 vs. $1,981) (both P&lt; 0.001). The substitution of more hospice care relative to inpatient care for men who died of prostate cancer resulted in lower total health care costs ($42,572 vs. $45,830; P&lt; 0.001) relative to men who died from non-prostate cancer causes. Conclusions: Among men with a diagnosis of prostate cancer who died between 2000 and 2007, those with prostate cancer-specific mortality had lower overall health care costs than those who died from other causes. Less aggressive inpatient care near the end of life may explain the differences in cost. Ongoing investigation of care at the end of life is warranted given recent changes in the treatment landscape of metastatic prostate cancer.

P573 Changes in resource utilisation in patients with Crohn's disease treated with adalimumab in routine clinical practice

P573 Changes in resource utilisation in patients with Crohn's disease treated with adalimumab in routine clinical practice

Clinical Trials in Orthopaedics Research. Part III. Overcoming Operational Challenges in the Design and Conduct of Randomized Clinical Trials in Orthopaedic Surgery

As we aspire to implement evidence-based medicine in the daily practice of orthopaedics, it is critical to understand the level of evidence that guides routine clinical decisions. Randomized controlled trials (RCTs) offer methodology for delivering the highest level of evidence1. Whereas the first RCTs were conducted half a century ago to test the efficacy of new pharmacologic agents, such trials are now being used increasingly to evaluate therapies other than medications, including surgery and behavioral interventions. Surgical RCTs involve additional complexity with regard to several key methodological components of the RCT: the willingness of patients to enroll, implementation of blinding (masking), and the impact of crossovers from one trial arm to another. The American Academy of Orthopaedic Surgeons (AAOS) and the Orthopaedic Research Society (ORS) sponsored a symposium on clinical trials in orthopaedic research in May 2009 at which each of these challenges was discussed2,3. Discussions during the symposium focused on offering suggestions regarding how to address these methodological issues during the design and implementation phases of a study. This paper summarizes key discussion points highlighted during the AAOS-ORS Symposium and comments on related issues, including compliance with nonsurgical regimens in studies comparing surgery with nonoperative treatment and the appropriate use of subgroup analysis. The paper concludes with suggestions regarding cost-effectiveness analysis in orthopaedic research. For an RCT to make a difference in the clinical management of musculoskeletal disorders, it must be planned carefully. In addition to detailed specification of the treatment regimen for each arm in the trial, it is critical to perform a careful analysis of the sample size required to conduct a trial that is conclusive (positive or negative). A study with an insufficient sample size may fail to detect a statistically significant difference between the arms of the study even …

No evidence for a role of competitive capabilities of adults in causing habitat segregation of diploid and hexaploid Senecio carniolicus (Asteracaeae).

Hexaploid individuals of Senecio carniolicus (Asteraceae) predominantly occur in dense swards while diploids prevail in open vegetation. We test whether this habitat segregation is due to differential responses to competition. Linear regression models were used to relate biomass and maximum leaf length of adults to vegetation cover within radii of 20 cm around target individuals. Biomass differed between ploidy levels, but was independent from vegetation cover in both cytotypes. Maximum leaf length of diploids increased with vegetation cover, but remained constant in hexaploids. This suggests that at the adult stage diploids respond to increasing competition by changes in plant architecture rather than changes in resource utilization, while hexaploids are unaffected by competition. Consequently, other factors, such as competitive interactions at earlier life stages, likely are responsible for habitat segregation of diploid and hexaploid S. carniolicus.

Behavioral changes following the collaborative development of an accounting information system

This research examines physician response to implementation of an activity-based costing (ABC) system developed and designed with physician input. We analyze changes in resource utilization for treatment of cataract patients and find changes in practice patterns, where physicians redeployed resources toward more severely ill patients and decreased average length of stay. We also find preliminary evidence of improvement in financial performance. We contribute to research investigating the influence of user participation on accounting system success, ABC system success, and hospital accounting information systems.

Vascular Surgery, ICU and HDU: A 14-Year Observational Study

Over the course of the past decade, numerous changes have occurred in the management of patients undergoing vascular surgical operations. The introduction of high dependency units (HDUs) has meant that many patients previously requiring observation in intensive care units (ICUs) are now managed in this new environment. In addition, many vascular patients may now be suitable for management on a vascular ward immediately following their surgery. This study reports the chronological changes in resource utilisation of patients undergoing major vascular surgery in a district general hospital over a 14-year period. Details of all patients admitted to either the ICU or HDU under the care of a single vascular surgeon during the period 1991-2004 were extracted from a prospectively maintained anaesthetic department database. Details of the age and gender of the patients were obtained together with source of admission, place of discharge and need for re-admission. Operative details for each patient were extracted from a prospectively maintained vascular surgery database including type of procedure undertaken and degree of urgency. During the 14-year period under study, there was a dramatic decrease in the use of ICU facilities for the management of vascular patients from 100% in 1991 to 36% in 2004. There was a corresponding increase in the use of HDU for major vascular cases during the same period from 0% to 66%. However, despite a significant increase in the total number of major vascular operations performed, from 67 in 1991 to 185 in 2004 as a result of sub-specialisation, overall use of all high-care facilities fell as the number of patients returned directly to the vascular ward increased from 34% in 1991 to 64% in 2004. The efficacy of the choice of management venue was confirmed by the observation that only 7.7% of those managed on ICU had been initially managed at a lower level of care. In addition, only 1.8% of patients managed on HDU had been admitted after initially being managed on the vascular ward. Sub-specialisation over the past decade has meant a significantly increased major vascular work-load. Since the introduction of the HDU, there has been a significant fall in the use of ICU facilities for routine cases. These changes in resource utilisation have significant implications in terms of budget allocation. It would appear that finances, in relation to vascular surgery, should be concentrated on expanding HDU facilities and ensuring vascular surgery expertise amongst ward nursing staff.

Impact of solifenacin on resource utilization, work productivity and health utility in overactive bladder patients switching from tolterodine ER

ABSTRACTObjective: Assess changes in resource utilization, work and activity impairment, and health utility among OAB patients continuing to have urgency symptoms with tolterodine ER 4 mg and willing to try solifenacin 5/10 mg.Research design and methods: This was an open-label, non-comparative, flexible-dosing, multicenter, 12-week study assessing the efficacy and safety of solifenacin 5/10 mg/day. Patients receiving tolterodine ER 4 mg/day for ≥4 weeks but continuing to experience residual urgency symptoms (≥3 urgency episodes/24 h) were enrolled into the study. After a 14-day washout, patients began treatment with solifenacin 5 mg/day with dosing adjustments allowed at Weeks 4 and 8.Main outcome measures: Outcomes were assessed using the Work Productivity and Activity Impairment Questionnaire – Specific Health Problem (WPAI-SHP), Health Utilities Index (HUI), and a resource utilization questionnaire administered at Pre-Washout and Week 12.Results: Patients (n = 440) reported significantly fewer physician office visits (p < 0.0001), UTIs (p < 0.0001), and pads/diapers (p = 0.0009) during the study period while receiving solifenacin 5/10 mg/day, compared with the Pre-Washout period when receiving tolterodine ER 4 mg/day. After 12 weeks of treatment with solifenacin 5/10 mg/day, patients reported a reduction in work time missed (p = 0.0017), less impairment while working (p < 0.0001), less overall work impairment (p < 0.0001) and a reduction in activity impairment (p < 0.0001) compared to Pre-Washout. There was no significant difference in health utility scores. Treatment-emergent adverse events were mostly anticholinergic in nature, and were mild to moderate in severity.Conclusion: Overall, solifenacin 5/10 mg/day improved work productivity, activity participation, and reduced medical care use in OAB patients who continued to have urgency symptoms with tolterodine ER 4 mg/day and wished to switch to solifenacin 5/10 mg. This was an open-label, non-comparative study; therefore, further research is needed to confirm these results.

Stable isotope natural abundances ( δ13C and δ15N) of the earthworm Eisenia fetida and other soil fauna living in two different vermicomposting environments

Manure heaps and vermicomposting systems are hotspots of heterotrophic activity supporting a high-detritivore biomass where epigeic earthworms interact intensively with bacteria, fungi and other soil fauna. We carried out a prospective study of the vermicomposting food webs using the natural abundance of stable C and N isotopes in 66 samples of soil fauna and the substrates in which the animals live in two systems: (i) a high-feeding-rate vermireactor, fed with pig slurry, and (ii) a farm manure vermicomposting heap fed with cattle manure. The aims of the study were specifically (i) to test the extent to which the isotopic signals in the earthworms resemble those of the substrates in which they live, (ii) to further our knowledge of the ontogenic changes in resource utilization of the earthworm Eisenia fetida, and (iii) to obtain information about the relative trophic position of the soil fauna in the food web of vermicomposting systems. Tissues of earthworms were significantly 15N-enriched (by 4–8‰) relative to fresh and mature manures in both vermicomposting systems. The δ 13C values of adult earthworms were not different from those of the fresh animal wastes in both vermicomposting systems, suggesting that adult worms preferred fresh manure than worked materials as carbon source. The little but significant enrichment in 15N observed in hatchlings living in the pig slurry vermicomposting bins relative to adult tissues likely reflect different feeding strategies, not observed in the cattle manure heap. Besides, hatchlings in the cattle manure heap appeared markedly depleted in 13C (by ∼5‰) relative to the adult earthworms, suggesting the use of a different source of carbon in the early stage. Diptera larvae presented very low values of δ 13C, likely suggesting a relevant role of methanotrophic bacteria in their diet. Based on the shifts in δ 15N, a taxon in the pig slurry vermicomposting bins may be assigned at least to three relative trophic positions separated by a 15N shift of 2‰, with Enchytraeida clearly in the lower position, adults and hatchlings of E. fetida and nematodes in an intermediate level, and Collembola at the higher position showing an enrichment of 9‰ relative to the substrate. In the cattle manure heap three trophic levels may be also identified, with larvae of Diptera and Coleoptera as the less 15N-enriched level, a general detritivore group in intermediate position, and finally a predatory taxa with a +9‰ shift comprised by Staphylinidae.

Carotid endarterectomy at the millennium: what interventional therapy must match.

Carotid endarterectomy (CEA) is supported by level 1 evidence as the standard treatment of severe carotid stenosis in both symptomatic and asymptomatic patients. As interventional techniques are emerging for treatment of this disease, this study was undertaken to provide a contemporary surgical standard for comparison to carotid stenting. During the interval 1989 to 1999, 2236 isolated CEAs were performed on 1897 patients (62% male, 36% symptomatic, 4.6% reoperative procedures). Study endpoints included perioperative events, patient survival, late incidence of stroke, anatomic durability of CEA, and resource utilization changes during the study. Variables associated with complications, long-term and stroke free survival, restenosis, and resource utilization were analyzed by univariate and multivariate analysis. Perioperative complications occurred in 5.5% of CEA procedures, including any stroke/death (1.4%), neck hematoma (1.7%), cardiac complications (0.5%), and cranial nerve injury (0.4%). Actuarial survival at 5 and 10 years was 72.4% (95% confidence interval [CI] 69.3-73.5) and 44.7% (95% CI 41.7-47.9) respectively, with coronary artery disease (P < 0.0018), chronic obstructive pulmonary disease (P < 0.00018) and diabetes mellitus (P < 0.0011) correlating with decreased longevity. The age- and sex-adjusted incidence of any stroke during follow-up was reduced by 22% (upper 0.35, lower 0.08) of predicted with the patient classification of hyperlipidemia (P < 0.0045) as the only protective factor. Analysis of CEA anatomic durability during a median follow-up period of 5.9 years identified a 7.7% failure rate (severe restenosis/occlusion, 4.5%; or reoperative CEA, 3.2%) with elevated serum cholesterol (P < 0.017) correlating with early restenosis. Resource utilization diminished (first versus last 2-year interval periods) for average hospital length of stay from 10.3 +/- 1.5 days to 4.3 +/- 0.7 days (P < 0.01) and preoperative contrast angiography from 87% +/- 1.4% to 10.3% +/- 4%. These data delineate the safety, durability, and effectiveness in long-term stroke prevention of CEA. They provide a standard to which emerging catheter-based therapies for carotid stenosis should be compared.

Managing distributed objects in peer-to-peer systems

Peer-to-peer systems that dynamically organize, interact and share resources are increasingly being deployed in large-scale environments. The location, intermittent connectivity, and organization of the peers have significant impact on meeting the quality of service requirements of distributed applications. This article presents the design, implementation, and empirical evaluation of a middleware architecture for managing distributed objects in peer-to-peer systems. The architecture consists of a self-organizing infrastructure that uses only local knowledge to dynamically form overlays of multiple peers and respond to changing processing and networking conditions; and a management layer that monitors the behavior of the applications transparently, schedules object invocations over multiple machines, and obtains accurate resource projections. The system works in a two-level feedback loop structure that uses measurements of elapsed time and resource loads to refine the initial estimates and revise the peer connections. Our empirical evaluation shows that the system manipulates the peer connections dynamically in response to changes in resource utilization to meet application end-to-end soft real-time requirements.

The dynamics of health care resource utilization.

Many pharmacoeconomic studies suffer from issues relating to the sensitivity of data and ability to accurately determine treatment-related costs. In addition, cost data generally are treated as static or constant variables. Our goal was to develop an approach to cost analysis that would allow us to appreciate the dynamic nature of health care resource utilization. By collecting detailed cost data on a daily basis and focusing on a narrow interval encompassing the infectious process, we were able to detect changes in resource utilization associated with management of the infectious process. This method also allowed us to assess and compare the dynamics of resource utilization among various patient groups.

Vascular 03

Over the course of the past decade, numerous changes have occurred in the management of patients undergoing vascular surgery operations. The introduction of high dependency units (HDUs) has meant that many patients previously requiring observation in intensive care units (ICUs) are now managed in this new environment. This study reports the chronological changes in resource utilization of patients undergoing major vascular surgery at a district general hospital (DGH). Details of all patients admitted to either the ICU or HDU under the care of a single vascular surgeon during the period 1991–2000 were extracted from the prospectively maintained departmental database. Details of the age and sex of patients were obtained together with source of admission, place of discharge and duration of stay. Operative details for each patient were extracted from a prospectively maintained vascular surgery database. Details of patients not attending either HDU or ICU during the postoperative phase were obtained from the same source. During the 10-year period under study, numerous changes in vascular surgery practice were observed. The HDU unit was opened in 1992. Subspecialization over the past decade has meant a significantly increased major vascular workload. Since the introduction of the HDU, there has been a significant fall in the use of ICU facilities for routine cases. These changes in resource utilization have significant implications in terms of budget allocation. It would appear that finances, in relation to vascular surgery, should be concentrated on expanding HDU facilities and ensuring vascular surgery expertise amongst ward nursing staff.

Home and Away: Comparisons of Resource Utilization by a Marine Species in Native and Invaded Habitats

The exotic Asian shore crab, Hemigrapsus sanguineus, was recently introduced to the northeastern coast of North America and during the 1990's breeding populations were established throughout southern New England. In 1997–1998, ecological studies of several co-occurring brachyuran crabs were conducted and in native (Tanabe Bay, Japan) and invaded (Long Island Sound, USA) habitats of H. sanguineus. Standardized comparisons of H. sanguineus were made between the 2 habitats using data on crab sizes, utilization of space, and food habits. Results revealed that (1) the resource use of H. sanguineus was quite different from that of other resident species in its invaded habitat, and (2) there were no substantial changes in resource utilization by H. sanguineus after it became established in the invaded habitat (relative to native Tanabe Bay). Differing patterns of resource use by H. sanguineus and other crabs in the invaded habitat, the lack of restriction in resource use by H. sanguineus following its introduction, and the climatological and physical similarities between native and invaded regions likely contributed to the successful invasion of H. sanguineus into rocky intertidal habitats in southern New England.

Habitat and Seasonality As Niche Axes in an Odonate Community

This study focuses on the coexistence of the dominant populations among 46 odonate species found in Bays Mountain Park, Sullivan County, Tennessee, USA. By monthly sampling of six aquatic habitats within the park, we established the larval biomass distributions of the 12 dominant populations across habitats and seasons and from these derive estimates of distributions along corresponding niche axes. We use an index proposed by Hurlbert (1978) to estimate niche specialization (breadth—1) and overlap on habitat and seasonal axes, both separately and simultaneously (two—dimensional analysis). This enables us to evaluate two possible mechanisms of coexistence in this community: resource partitioning (i.e., differing time—average patterns of resource utilization among competitors) and ecological shift (i.e., nonevolutionary change in resource utilization in response to competition). Three results support the resource—partitioning mechanism: 1) Competition coefficients, obtained by dividing niche overlap values by the appropriate niche specialization values, are all less than one; this indicates that each population should inhibit its own access to a limited food supply more than it inhibits the access of the other populations. 2) Though little or no complementarity between the habitat and seasonality axes is apparent when single—axis index values are examined, the two—dimensional competition coefficients are slightly smaller on average than the product of single—axis means, suggesting two—dimensional complementarity. 3) There are about the same number of consistent 3—yr trends in specialization and overlap as would be expected by chance, suggesting a relatively persistent arrangement of odonate niches in niche space. But the ecological shift mechanism may be operating within or between those populations that do exhibit consistent 3—yr trends in specialization or overlap; more of these values consistently decrease than would be expected by chance. The six populations that comprise the detritus—submersed macrophyte guild account for most of the larval biomass, and the dominant population within the guild (and the community as a whole) is the semiovoltine anisopteran Tetragoneuria cynosura. A particularly intense interaction, as indicated by the competition coefficients, is between the abundant zygopterans Enallagma traviatum and E. signantum; unusually high specializations and overlap were observed for the rush—dwelling zygopterans Ischnura verticalis and I. posita.